1. Field of the Invention
The present invention relates to a scanner, and more specifically, to a scanner comprising a locking module for moving a light source with a carriage simultaneously.
2. Description of the Prior Art
In general, scanners on the market are divided into three groups according to the media they scan, positive scanners, negative scanners (for photo films and projective films etc.), and scanners which support both positive and negative media. As a scanner scans a negative image, there are two types of light source modules can be selected; the first type is immovable and has a large lighting area, the second type is movable and has a small lighting area. For the immovable light source module, when the scanner scans a negative image, a uniform light source is provided for the whole region on the scanning platform. This ensures that the light passes through the transparent region of the negative image and is received by photoelectric sensors set on a carriage positioned below the scanning platform, but the light cannot pass through the opaque region of the negative image. Next, according to the received light, the photoelectric sensor produces an image corresponding to the negative image. Because this method requires a brighter and more uniform light source, the cost is high.
For the movable light source module, the negative image is divided into a plurality of small regions when the scanner is scanning. Next, a driving module drives the light source module and the carriage to move simultaneously for utilizing photoelectric sensors set on the carriage to scan these small regions continuously. Finally, all scanning images scanned at all small regions are combined to form a fully scanned image. It is unnecessary to provide a light source for lighting up all scanning regions, therefore resulting in a lower cost than the immovable light source module, but this method requires additional transmissions (like gears or belts) to form the driving module to drive the light source module. As mentioned above, the driving module has to drive the light source module and the carriage simultaneously for scanning completely.
In conclusion, taking the cost factor into consideration, traditional scanners usually select the second type of light source module discussed above for scanning media, but the disadvantage is that they require additional mechanical apparatus for driving the light source module to move with the carriage simultaneously.